The Sierra Gorda copper-molybdenum operation in Chile has approved a major brownfield expansion that will increase processing capacity by 25% and lift expected copper-equivalent production by around 30%. The project will add a fourth grinding line, increasing annual ore-processing capacity from approximately 48 million tonnes to 60 million tonnes.
Sierra Gorda Expansion Targets 2030 Production
The expansion is expected to require approximately US$725 million in growth capital between the 2027 and 2030 financial years. The investment will cover additional grinding, crushing and flotation equipment, together with supporting process infrastructure.
KGHM Polska Miedź owns 55% of Sierra Gorda, while South32 holds the remaining 45%. The partners are expected to finance the expansion through operating cash flow and joint-venture debt rather than issuing new equity. First production from the expanded facilities is targeted for the middle of South32’s 2030 financial year, with the operation expected to reach full production rates during 2031.
Once the expansion is fully operational, Sierra Gorda is targeting average annual payable production of approximately 195,000 tonnes of copper, 6,000 tonnes of molybdenum, 58,000 ounces of gold and 1.7 million ounces of silver. That would translate into around 250,000 tonnes of copper-equivalent production per year, roughly 30% above current levels. Higher throughput is also expected to reduce average operating costs by approximately 10%, providing an important economic benefit from the larger processing operation.
Brownfield Infrastructure Limits Capital Requirements
The project benefits from Sierra Gorda’s existing power, water, tailings and mine infrastructure, reducing the amount of new infrastructure required compared with a greenfield development. The disclosed capital intensity is approximately US$21,000 for each annual tonne of copper-equivalent capacity, reflecting the advantages of expanding an established mining complex.
The economic study estimates an internal rate of return of approximately 20% using a long-term copper price of US$5 per pound. At a US$6-per-pound copper price, the estimated return rises to around 23%. Those assumptions provide attractive headline economics, but they also warrant sensitivity analysis. Copper prices below the base case, construction-cost inflation or delays in achieving planned throughput could materially affect returns.
Higher Throughput Creates Operational Challenges
The principal risks are linked to integrating the new equipment into an operating mine rather than building an entirely new operation. Sierra Gorda will need to coordinate construction and shutdown activities while maintaining existing production. The expanded grinding and flotation circuits must also deliver the expected performance as ore characteristics change.
Higher processing volumes could create additional pressure on flotation recovery, grinding efficiency and downstream infrastructure. Maintaining recoveries while increasing throughput will therefore be critical to achieving the projected production gains. If the project is delivered on schedule and performs as expected, the fourth grinding line will transform Sierra Gorda’s production profile and strengthen its position as a significant copper, molybdenum, gold and silver producer in Chile. The key milestones will now be construction execution, financing, equipment integration and the ability to reach full production rates during 2031.
